I have had MySCXD for about a yearand 1/2 and it suddeen was making a noise w/out anything even plugged into it ,so checked the power tubes to see if they were plugged into the socket and they were the wrong tubes. They are supposed to be 6v6 but were 6l6 . someone at the factory made a mistake .did this do damage ? any of you experts have any ideas ?
Wow, that's quite unusual - never heard of this before with a factory Fender. Oh well, you're the first!
I'm guessing you're OK. Here's why.
I don't have any experience with the Super Champ XD. However, I do with replacing the stock 6V6s w/6L6s in Deluxe Reverbs. The 6L6s draw more current so you have to rebias but the trannys are sufficiently robust to handle the replacement tubes. With a DR Reissue, you're done with a rebias. For an older BF or SF, it's usually advised to replace the filter caps (and perhaps the screen resistors) to ensure you're safe to handle the extra juice. (Do not, however, try this trick with a Princeton Reverb - the trannys can't take it).
If you ran the amp and it worked for a year and a half with the 6L6s, I feel pretty confident that the amp handled it fine. If it hadn't, you'd have known sooner! But this is just my best guess.
